Radio tuning means



Aug. 12, 1941. w. E. NEWMAN RADIO TUNING MEANS Filed Feb. 29, 1940 1 I Supentor mar/1;! B

(Ittorneg Patented Aug. 12, 1941 RADIO TUNING MEANS William E. Newman, Moorestown, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application February 29, 1940, Serial No. 321,544-

7 Claims.

The present invention relates to radio tuning means particularly adapted for the tuning of signal-conveying circuits which are variably tunable in unison, and has for its object to provide an improved tuning means of that character for a plurality of signal-conveying circuits in which at least one of the circuits includes variable inductance tuning of the movable core type.

In radio signalling systems, the conjoint or gang-tuning of a plurality of circuits ordinarily involves tuning the circuits through the same or through constantly differing frequency ranges, and with the same or differing rates of frequency or inductance change one with respect to the other to provide tracking of the tuning of the circuits.

In a superheterodyne receiver, for example, the R. F. or signal input circuit and the oscillator circuit, when conjointly tunable by unitary means, must vary at differing rates in tuning to provide the constant output or intermediate frequency, because of the difference in ratios of frequency change.

It is, therefore, a still further object of the present invention to provide tuning means including a movable core variable inductance in at, least one of a plurality of conjointly tunable circuits which may be adjusted individually to provide a predetermined tuning characteristic as the core is movedfor tracking and other purposes, as desired.

It has been found that the spacing between the core and the winding turns of a variable, movable core inductance may be adjusted both as to the entire coil or winding and certain individual turns or groups of turns to adjust the frequency response of the coil at one end of a tuning range and throughout the tuning movement of the core, to effect any desired tuning characteristic within limits which provide for effective tracking with other circuits, which may also be similarly variable-inductance tuned if desired.

The invention will, however, be better understood from the following description when considered in connection with the accompanying drawing, and its scope is pointed out in the appended claims.

In the drawing, Figure 1 is a view in perspective schematically representing a portion of a variable, movable core inductance winding in the process of being formed in accordance with the invention;

Figure 2 is an end view, partly in section and V on an enlarged scale, of the completed winding of Figure 1 showing one embodiment of the invention;

Figure 3 is a plan view, partly in section, showing the inductance element of Figures 1 and 2 embodied in a tuning means for a pair of tunable circuits arranged for conjoint control of tuning in the two circuits and tracking in accordance with the invention;

Figure 4 is a schematic circuit diagram showing two conjointly tunable signal circuits for which the tuning means of Figure 3 is particularly adapted; and

Figures 5 and 6 are end views, partly in section and on an enlarged scale, of modifications of the inductance element of Figures 1 and 2 also embodying the invention.

Referring to Figs. 1 to 4, inclusive, an inductance winding i having a deformable portion 6 is wound on a coil form I in the usual solenoid form, the deformable portion 6 being included in each turn of the winding by spacing the winding turns from the coil form by forming strip 8 extending longitudinally or axially along the form 4 and lying against the coil form, as shown, to pro vide a bulge in the winding along the length thereof.

In practice, the turns are wound close together or spaced, as may bedesired, over the coil form and forming strip, and the latter is removed when the winding is completed, leaving an axially or longitudinally extending portion of the winding self-supporting or unsupported, whereby a plurality of consecutive turns may be pressed down or toward the coil form and toward or away from a movable tuning core element 9 at one or more positions along the length of the winding, such as indicated at H). In the present example the core element is provided within the winding although it may be arranged in any. other suitable form to move relative to and along the winding.

It has been found that this may be used to adjust the inductance of various coils in manufacture and, when utilized in a tuning system, is effective to cause a variation in the rate of change of the inductance of the winding as the core is moved axially in tuning. Thus, in Fig. 3, for

I example, movement of the core 8 under the deformed section III will cause a different rate of change in inductance and hence of the tuning than when moving under the sections not so deformed.

ductances l3 and it respectively, the core 9 is connected with a variable tuning element of the second circuit, such as the movable core l3 in an inductance winding It for such circuit.

A suitable mechanical arrangement for mounting the coils and moving the cores, as shown in Fig. 3, comprising a supporting element ii in which the coil forms 1 and ii are secured after axial movement to adjust and fix the relative depth of penetration of the cores in the coils. A drive mechanism for the cores may comprise an adjustable yoke member ll, connected with push rods [8 and i9 extending from the cores in parallel relation as shown, and passing through a fixed guide member 20, which also carries a rotary screw-threaded driving member 2| for the yoke ll. Rotation of the member M by suitable means such as a manual control knob 22, causes the yoke to be moved longitudinally and moves the cores 9 and It into and out of the windings conjointly, thereby to effect variation of the tuning of the two circuits simultaneously.

Assuming that the inductances and I4 are similar, with core members of the same size and penetrating to the same depth, slight manufacturing differences may cause the tuning of the two circuits to vary in frequency one from the other. With tuning means shown, however, the individual turns or a group of turns may be pressed toward the core to adjust the inductance of one or both windings, thereby to cause track'- ing of the two circuits throughout the tuning movement.

For the highest inductance and lowest frequency tuning position of the cores 9 and I3, the two circuits in which the windings I and H are extreme care in winding, since each coil is inlocated may be brought into initial alignment by rotation of one of the cores, such as the core 9, to increase and decrease the spacing of the core throughout the length thereof with respect to the winding as a whole. This may be accomplished as shown in Fig. 5 by mounting a cylindrical core "23 in an eccentric relation to the central driving rod l9, so that, by rotation of the rod, the core maybe worked towards and away from the deformable winding section [0, thereby to adjust the over-all inductance of the coil, A similar adjustment may be provided by a flattened portion 24 on a core 25, as indicated in Fig. 6. This provides a relatively small variation in inductance sufllcient to align the circuits at the low frequency end of the tuning range and thereby provide tracking initially. This may be continued throughout the movement of the core being held in position longitudinally by two collars 26 secured to the rod, as shown, so that the latter may be rotated to'provid adjustment of the core after which it is secured to the yoke I! by suitable means such as aset screw 21, as is also the rod ll. Any other suitable arrange ment may be provided, however, for permitting rotation of the push rods to rotate the cores or either of them. The rotation of the core is facilitated by providinga screw driver slot 29 or other suitable means at one end of each rod to be rotatably adjusted.

An advantage in the use of th resent tuning means lies in the factthat fixed capacitors 30 may be provided in each circuit withoutaddi tional means for effecting tracking other than the inductances per se, any or all of which may be adjusted for initial tracking and tracking throughout the variable tuning movement of the core or cores in the manner shown and described herein.

It should be understood that the tuning means is not limited to use in connection with the oscillator and R. F. tuning circuits of a superheterodyne receiver, but it may be used in any signalling apparatus having a tunable circuit adapted for use with an inductance winding. The inductance of which may be varied.

It has also the advantage that inductances for a plurality of tuned circuits may be adjusted each to a standard in manufacture without exercising dividually adjustable ininductance for one or more positions of the movable tuning core.

I claim as my invention:

1. Variable inductance tuning means comprising a solenoid'winding, and a magnetic tuning core element axially movable relative to and along said winding to vary the inductance thereof, said winding having a self-supporting axially extending section including a portion of a plurality of winding turns providing radially adjustable spacing between said turns in said section and the path of movement of the core element, whereby the core is movable in variably spaced relation with respect to said turns to provide adjustment of the rat of change of inductance a movable magnetic core therefor, and a tubular coil form for receiving said core and supporting said winding through a portion of each turn thereof, said winding having a longitudinally extending radially deformable section including an unsupported portion of each winding turn separated and raised from the coil form.

3. Tuning means for radio signal circuits including in combination, a solenoid inductance winding, means for supporting said winding through a portion of each turn thereof, said winding having a longitudinally extending deformable section including an unsupported portion' of each winding turn, and an axially movable tuning core element for said winding, the spacing between the winding and the core being adjustable by depressing the winding turns in said area in the direction of the path of movecluding in combination, an inductancewindi'ng,v

means for supporting said winding through a portion of each turn thereof, said winding having a longitudinally extending deformable section including an unsupported portion of each winding turn, atuning core element for said winding, the spacing between the winding and the core being adjustable 'by deformation of the winding turns in said area to adjust the inductance of said winding, means providing movement of said core axially with respect-to the winding, and means for rotating said core, to provide tuning control and initial tuning adjustment of said winding.

6. Tuning means for radio signal circuits comprising a solenoid inductance winding having a longitudinally extending deformable section including a portion of a plurality of consecutive winding turns, a tuning core axially movablewith respect to the. winding along said section, the spacing between the winding and the core along said section being adjustable by deformationof the winding turns in said area; and means responsive to rotating of said core providing additional adjustment of the spacing between the core and winding.

7. Variable inductance tuning means for a plurality of radio signal circuits in unison, comprising a plurality of cylindrical coil forms, an axially movable tuning core in each coil form,

means providing gang tuning movement of said cores, a solenoid winding carried by each of said coil forms in association with said cores, at least one of said windings having a self-supporting section extending along a portion of its length and including a plurality of winding turns individually adjustably movable radially toward and away from the path of movement of the core thereby to provide adjustment of the rate of change of inductance with movement of the core, and means-for supporting said coil forms providing axial adjustment thereof to adjust the relative depth of penetration of the cores within said coil forms and windings in response to joint tuning movement.

WILLIAM E. NEWMAN. 

